| 摘要 |
<p>PURPOSE:To immediately detect the contact of a metal boring rod of a boring machine with a metal pipe buried in the ground when the ground is digged by the metal boring rod. CONSTITUTION:Voltage from a DC powre supply 6 is applied between a boring rod 2 and an earth rod 5 which is driven in soil 3. The applied voltage is adjusted so that voltage between the boring rod and a saturated copper sulfate reference electrode 8 which is in contact with the ground becomes zero. When the boring rod 2 touches a metal object buried in the ground 4, voltage between the boring rod and reference electrode changes abruptly, or current of the power supply increases. Thus, it is possible to detect the contact of boring rod 2 with the metal object buried in the ground 4 securely.</p> |
